Development of New Thermal Protection Systems Based on Polysiloxane/Silica Composites: Properties Characterization I

Transcription

1 Development of New Thermal Protection Systems Based on Polysiloxane/Silica Composites: Properties Characterization I Kurt Schellhase 1, Robert Brushaber 1,2, Hao Wu 1, Joseph H. Koo 1 *, Jarrod Buffy 3, and Eric Schmid 4 1 The University of Texas at Austin, Dept. of Mechanical Engineering, 204 E. Dean Keeton St., C2200, Austin, TX Texas Research Institute Austin, Inc., 9063 Bee Caves Road, Austin, TX Dyna-Glas, 2100 North Wilkinson Way, Perrysburg, OH South Dakota School of Mines & Technology, Composites and Polymer Engineering (CAPE) Laboratory, 501 E. Saint Joseph Street, Rapid City, SD *Corresponding author: jkoo@mail.utexas.edu 1

2 Today s Presentation Background and Motivation Material Systems Characterization Methods Results Conclusion Future Work 2

3 Background Want to investigate new ablative material systems Need for materials which can withstand harsher environments o Rocket Motors o TPS Materials for Re-entry Vehicle o Nose Cones Atmospheric Probes o Vertical Launching Systems o Fire Prevention Trains, Submarines, etc. 3

4 Ablative Materials Resist thermochemical erosion caused by harsh environment Formation of the protective char layer Different mechanisms for different materials, no one size fits all ablative Current SOTA resins: SC-1008, PT-15 4

5 SC-1008 MIL-standard phenolic resole resin manufactured by Hexion Typically carbon or silica fiber reinforcement Foamed versions of phenolic used for low density ablators Lots of data collected Diverse applications, from TPS materials to rocket motor materials Relatively cheap 5

6 PT-15 Low viscosity cyanate ester (CE) resin manufactured by Lonza Typically glass reinforcement Different manufacturer, but CE/3D-quartz used as part of Orion heat shield/compression pad More expensive 6

7 DT-1116 Inorganic matrix, utilizing a mixture of polysiloxane chemistries manufactured Dyna-Glas Technologies LLC o Low thermal transfer o Excellent chemical resistance o Excellent thermal stability o Low heat release rate and heat release capacity o Low viscosity and cure temperatures Will be examining two proprietary formulations DT and DT

8 Material Characterization Thermogravimetric Analysis Thermal Stability & Char Yield Microscale Combustion Calorimeter Heat Release Rate and Capacity Kinetic Parameters Modeling Activation Energy 8

9 Char Yield Study 1. Dry the TGA sample 150C for 30min 2. Consistent sample size 20mg 3. TGA heating rate of 20 C/min in nitrogen. 4. Char yield is defined as the %mass remaining at 1,000 C. Developed based on a NASA report on PICA 9

10 Char Yield Study Char yield results for SC-1008, PT-15, DT1116-1, and DT

11 Char Yield Study dtga for SC-1008, PT-15, DT1116-1, and DT

12 SC-1008 phenolic at heating rates of 5, 10, 20, and 40ºC/min 12

13 PT-15 cynate ester at heating rates of 5, 10, 20, and 40ºC/min 13

14 DT polysiloxane at heating rates of 5, 10, 20, and 40ºC/min 14

15 DT polysiloxane at heating rates of 5, 10, 20, and 40ºC/min 15

16 Decomposition temperature (T d ) of 10% mass loss temperature Weight % at 1,000ºC 16

17 Kinetic Parameters The rate of thermal decomposition of polymers can be modeled by the kinetic rate equation Need to have the correct kinetic parameters in order to have a accurate model Used the isoconversion method to solve for the kinetic parameters 17

18 Kinetic parameters Due to the multiple stage degradation and the high residual mass of the polysiloxane resins, the activation energy could not be accurately determined. Model we are using works well with the single stage, 1 st order decomposition Good model for some resins, but gives nonsensical activation energy values for DT

19 Flammability Properties Microscale Combustion Calorimeter Lab scale for small sizes Screening tool Good alternative to a cone calorimeter 19

20 Flammability Properties Typical heat release curves for the four resin systems 20

21 Flammability Properties Comparison of the Heat Release Capacities for the four resin systems 21

22 Conclusion DT exhibited the best results with 87% char yield. An increase of ~54% compared to phenolic and cyanate ester resins. DT-1116 had a HRC of 36 J/g-K. SC-1008 phenolic s HRC was 48% higher at J/g-K and PT-15 cyanate ester s HRC was 443% higher at J/g-K Activation energy could not be accurately determined with the current models. A better model is needed. 22

23 Future Work Dispersion of nanosilica into the resin, and additional characterization Incorporation of silica fabric into the polysiloxane resin Ablation testing using Oxygen-Acetylene Test Bed (OTB) and Inductively Coupled Plasma (ICP) torch Mechanical properties 23

24 Questions?